From 2d96619c675966eae5ecb71300e884a15a35efe9 Mon Sep 17 00:00:00 2001
From: gdlbo <41114720+gdlbo@users.noreply.github.com>
Date: Sat, 13 May 2023 15:43:29 +0300
Subject: [PATCH] Create Multithreading.java

---
 .../lite/downloaders/Multithreading.java      | 84 +++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 app/src/main/java/ru/vtosters/lite/downloaders/Multithreading.java

diff --git a/app/src/main/java/ru/vtosters/lite/downloaders/Multithreading.java b/app/src/main/java/ru/vtosters/lite/downloaders/Multithreading.java
new file mode 100644
index 000000000..f07e97f5d
--- /dev/null
+++ b/app/src/main/java/ru/vtosters/lite/downloaders/Multithreading.java
@@ -0,0 +1,84 @@
+package ru.vtosters.lite.downloaders;
+
+import android.util.Log;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.RandomAccessFile;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+public class Multithreading {
+    public static void download(URL url, File f, int threadCount) {
+        try {
+            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+            connection.setRequestMethod("GET");
+            int responseCode = connection.getResponseCode();
+            if (responseCode == HttpURLConnection.HTTP_OK) {
+                int fileSize = connection.getContentLength();
+                connection.disconnect();
+                RandomAccessFile file = new RandomAccessFile(f, "rw");
+                file.setLength(fileSize);
+                file.close();
+                if (threadCount == 0) threadCount = 4;
+                int partSize = fileSize / threadCount;
+                DownloadThread[] threads = new DownloadThread[threadCount];
+                for (int i = 0; i < threadCount; i++) {
+                    int startByte = i * partSize;
+                    int endByte = (i + 1) * partSize - 1;
+                    if (i == threadCount - 1) {
+                        endByte = fileSize - 1;
+                    }
+                    DownloadThread thread = new DownloadThread(i, url, f.getName(), startByte, endByte);
+                    thread.start();
+                    threads[i] = thread;
+                }
+                for (DownloadThread thread : threads) {
+                    thread.join();
+                }
+            } else {
+                Log.d("Multithreading", "Error, code: " + responseCode);
+            }
+        } catch (IOException | InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+    static class DownloadThread extends Thread {
+        private final int threadId;
+        private final URL url;
+        private final String fileName;
+        private final int startByte;
+        private final int endByte;
+
+        public DownloadThread(int threadId, URL url, String fileName, int startByte, int endByte) {
+            this.threadId = threadId;
+            this.url = url;
+            this.fileName = fileName;
+            this.startByte = startByte;
+            this.endByte = endByte;
+        }
+
+        @Override
+        public void run() {
+            try {
+                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+                connection.setRequestProperty("Range", "bytes=" + startByte + "-" + endByte);
+                InputStream input = connection.getInputStream();
+                RandomAccessFile file = new RandomAccessFile(fileName, "rw");
+                file.seek(startByte);
+                byte[] buffer = new byte[1024];
+                int length = input.read(buffer);
+                while (length != -1) {
+                    file.write(buffer, 0, length);
+                    length = input.read(buffer);
+                }
+                file.close();
+                input.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}